Before I dive into trying to understand the inner workings of
autoconf, has anyone here got zarafa's new opensource release to
compile on NetBSD? It looks like a decent contender to replace
exchange at a number of my client sites.

I'm not sure why you need to understand inner workings of autoconf
when you want to run zarafa exchange suite.

./configure fails to find ncurses even though it's installed from
pkgsrc. Before I spend a couple of hours fiddling with it, if anyone
else has it working, it'd be nice to know I'm not flogging a dead
horse.

$ ./configure --prefix="/where you wan files to be installed"
LDFLAGS="-L/usr/pkg/lib"

Maybe you should also use -R/usr/pkg/lib in LDFLAGS (runtime)

"/where you wan files to be installed" i use /usr/local or sometimes my
homedir

also -/configure --help | grep ncurse, might give you something like
with-ncurses
and set that to
with-nurses=/usr/pkg/lib
Then you dont have to use LDFLAGS

I wanted to test it before i wrote it, but i couldnt find a source
package to download without registering (didnt look long :))